p2p: add basic RLPx frame I/O
This commit is contained in:
Felix Lange
parent
15f491e500
commit
936dd0f3bc
129
p2p/rlpx.go
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129
p2p/rlpx.go
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@ -0,0 +1,129 @@
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package p2p
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/hmac"
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"errors"
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"hash"
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"io"
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"github.com/ethereum/go-ethereum/rlp"
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)
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var (
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zeroHeader = []byte{0xC2, 0x80, 0x80}
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zero16 = make([]byte, 16)
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)
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type rlpxFrameRW struct {
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conn io.ReadWriter
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macCipher cipher.Block
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egressMAC hash.Hash
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ingressMAC hash.Hash
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}
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func newRlpxFrameRW(conn io.ReadWriter, macSecret []byte, egressMAC, ingressMAC hash.Hash) *rlpxFrameRW {
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cipher, err := aes.NewCipher(macSecret)
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if err != nil {
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panic("invalid macSecret: " + err.Error())
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}
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return &rlpxFrameRW{conn: conn, macCipher: cipher, egressMAC: egressMAC, ingressMAC: ingressMAC}
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}
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func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
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ptype, _ := rlp.EncodeToBytes(msg.Code)
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// write header
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headbuf := make([]byte, 32)
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fsize := uint32(len(ptype)) + msg.Size
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putInt24(fsize, headbuf) // TODO: check overflow
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copy(headbuf[3:], zeroHeader)
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copy(headbuf[16:], updateHeaderMAC(rw.egressMAC, rw.macCipher, headbuf[:16]))
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if _, err := rw.conn.Write(headbuf); err != nil {
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return err
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}
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// write frame, updating the egress MAC while writing to conn.
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tee := io.MultiWriter(rw.conn, rw.egressMAC)
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if _, err := tee.Write(ptype); err != nil {
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return err
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}
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if _, err := io.Copy(tee, msg.Payload); err != nil {
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return err
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}
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if padding := fsize % 16; padding > 0 {
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if _, err := tee.Write(zero16[:16-padding]); err != nil {
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return err
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}
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}
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// write packet-mac. egress MAC is up to date because
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// frame content was written to it as well.
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_, err := rw.conn.Write(rw.egressMAC.Sum(nil))
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return err
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}
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func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
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// read the header
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headbuf := make([]byte, 32)
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if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
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return msg, err
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}
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fsize := readInt24(headbuf)
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// ignore protocol type for now
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shouldMAC := updateHeaderMAC(rw.ingressMAC, rw.macCipher, headbuf[:16])
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if !hmac.Equal(shouldMAC[:16], headbuf[16:]) {
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return msg, errors.New("bad header MAC")
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}
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// read the frame content
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framebuf := make([]byte, fsize)
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if _, err := io.ReadFull(rw.conn, framebuf); err != nil {
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return msg, err
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}
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rw.ingressMAC.Write(framebuf)
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if padding := fsize % 16; padding > 0 {
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if _, err := io.CopyN(rw.ingressMAC, rw.conn, int64(16-padding)); err != nil {
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return msg, err
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}
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}
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// read and validate frame MAC. we can re-use headbuf for that.
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if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
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return msg, err
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}
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if !hmac.Equal(rw.ingressMAC.Sum(nil), headbuf) {
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return msg, errors.New("bad frame MAC")
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}
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// decode message code
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content := bytes.NewReader(framebuf)
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if err := rlp.Decode(content, &msg.Code); err != nil {
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return msg, err
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}
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msg.Size = uint32(content.Len())
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msg.Payload = content
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return msg, nil
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}
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func updateHeaderMAC(mac hash.Hash, block cipher.Block, header []byte) []byte {
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aesbuf := make([]byte, aes.BlockSize)
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block.Encrypt(aesbuf, mac.Sum(nil))
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for i := range aesbuf {
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aesbuf[i] ^= header[i]
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}
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mac.Write(aesbuf)
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return mac.Sum(nil)
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}
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func readInt24(b []byte) uint32 {
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return uint32(b[2]) | uint32(b[1])<<8 | uint32(b[0])<<16
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}
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func putInt24(v uint32, b []byte) {
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b[0] = byte(v >> 16)
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b[1] = byte(v >> 8)
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b[2] = byte(v)
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}
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123
p2p/rlpx_test.go
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123
p2p/rlpx_test.go
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@ -0,0 +1,123 @@
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package p2p
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import (
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"bytes"
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"crypto/rand"
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"encoding/hex"
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"fmt"
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"io/ioutil"
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"strings"
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"testing"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/sha3"
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"github.com/ethereum/go-ethereum/rlp"
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)
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func TestRlpxFrameFake(t *testing.T) {
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buf := new(bytes.Buffer)
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secret := crypto.Sha3()
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hash := fakeHash([]byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})
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rw := newRlpxFrameRW(buf, secret, hash, hash)
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golden := unhex(`
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000006C2808000000000000000000000
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01010101010101010101010101010101
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08C40102030400000000000000000000
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01010101010101010101010101010101
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01010101010101010101010101010101
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`)
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// Check WriteMsg. This puts a message into the buffer.
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if err := EncodeMsg(rw, 8, []interface{}{1, 2, 3, 4}); err != nil {
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t.Fatalf("WriteMsg error: %v", err)
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}
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written := buf.Bytes()
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if !bytes.Equal(written, golden) {
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t.Fatalf("output mismatch:\n got: %x\n want: %x", written, golden)
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}
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// Check ReadMsg. It reads the message encoded by WriteMsg, which
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// is equivalent to the golden message above.
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msg, err := rw.ReadMsg()
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if err != nil {
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t.Fatalf("ReadMsg error: %v", err)
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}
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if msg.Size != 5 {
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t.Errorf("msg size mismatch: got %d, want %d", msg.Size, 5)
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}
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if msg.Code != 8 {
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t.Errorf("msg code mismatch: got %d, want %d", msg.Code, 8)
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}
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payload, _ := ioutil.ReadAll(msg.Payload)
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wantPayload := unhex("C401020304")
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if !bytes.Equal(payload, wantPayload) {
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t.Errorf("msg payload mismatch:\ngot %x\nwant %x", payload, wantPayload)
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}
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}
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type fakeHash []byte
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func (fakeHash) Write(p []byte) (int, error) { return len(p), nil }
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func (fakeHash) Reset() {}
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func (fakeHash) BlockSize() int { return 0 }
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func (h fakeHash) Size() int { return len(h) }
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func (h fakeHash) Sum(b []byte) []byte { return append(b, h...) }
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func unhex(str string) []byte {
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b, err := hex.DecodeString(strings.Replace(str, "\n", "", -1))
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if err != nil {
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panic(fmt.Sprintf("invalid hex string: %q", str))
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}
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return b
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}
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func TestRlpxFrameRW(t *testing.T) {
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var (
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macSecret = make([]byte, 16)
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egressMACinit = make([]byte, 32)
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ingressMACinit = make([]byte, 32)
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)
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for _, s := range [][]byte{macSecret, egressMACinit, ingressMACinit} {
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rand.Read(s)
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}
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conn := new(bytes.Buffer)
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em1 := sha3.NewKeccak256()
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em1.Write(egressMACinit)
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im1 := sha3.NewKeccak256()
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im1.Write(ingressMACinit)
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rw1 := newRlpxFrameRW(conn, macSecret, em1, im1)
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em2 := sha3.NewKeccak256()
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em2.Write(ingressMACinit)
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im2 := sha3.NewKeccak256()
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im2.Write(egressMACinit)
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rw2 := newRlpxFrameRW(conn, macSecret, em2, im2)
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// send some messages
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for i := 0; i < 10; i++ {
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// write message into conn buffer
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wmsg := []interface{}{"foo", "bar", strings.Repeat("test", i)}
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err := EncodeMsg(rw1, uint64(i), wmsg)
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if err != nil {
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t.Fatalf("WriteMsg error (i=%d): %v", i, err)
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}
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// read message that rw1 just wrote
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msg, err := rw2.ReadMsg()
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if err != nil {
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t.Fatalf("ReadMsg error (i=%d): %v", i, err)
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}
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if msg.Code != uint64(i) {
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t.Fatalf("msg code mismatch: got %d, want %d", msg.Code, i)
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}
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payload, _ := ioutil.ReadAll(msg.Payload)
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wantPayload, _ := rlp.EncodeToBytes(wmsg)
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if !bytes.Equal(payload, wantPayload) {
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t.Fatalf("msg payload mismatch:\ngot %x\nwant %x", payload, wantPayload)
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}
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}
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}
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